1. Field of the Invention
The present invention relates generally to internal combustion engines, and in particular relates to techniques which are designed to prevent undesirable forward movement of the cam shaft, commonly referred to as "cam walk", during high performance operation of an automotive engine.
2. Description of the Prior Art
Stock car racing is a very popular sport in the United States. Participants in this sport constantly seek to improve engine performance and design, and many engine developments which originate in the stock car racing sport eventually are incorporated in assembly line production of automobile engines.
Conventional stock engines, particularly those manufactured by the Chevrolet Division of General Motors Corporation, utilize a timing gear cover which is a stamped piece of sheet metal, which is bolted to the engine block over the extremity of the cam shaft, the timing gear and the timing chain assembly, and includes a hole designed to accept a seal for the front of the crank shaft, with a conventional gasket positioned between the cover and the engine block.
When conventional stock car engines employing conventional covers of the type described above are subjected to high performance, high speed conditions such as are normally incurred during stock car racing events, frequently the extremity of the cam shaft, by virture of the centrifugal force of that shaft, is forced outward and comes in contact with the sheet metal cover. Under sustained high performance conditions, the extremity of the cam shaft often dents the cover, and may destroy the seal between the cover and the engine block. Additionally, the fricion caused by movement of the cam shaft against the cover frequently results in reduced engine efficiency, erratic timing control, worn distributor gears and broken timing chains.
To reduce the serious effects of cam walk, there has been used in the past spacers which are inserted between the extremity of the cam shaft and the conventional sheet metal cover of the type described above. However, these spacers have proved to be unsatisfactory in sustained high performance operation in racing engines.